Method for recovering the fibrous material from sugar cane



' No Drawing.

Patented Nov. 25, 1930 UNITED STATES PATENT OFFICE JOAQUIN JULIO DE LAROZA,.SR-, OF BROOKLYN, NEW YORK, ASSIGNOR TO BAG ASSE PRODUCTSCORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK METHOD FORRECOVERING THE FIBROUS MATERIAL FROM SUGAR CANE This invention relatesto a method for recovering the fibrous material from sugar cane, andghasfor an object to provide for theproduction of soft, strong, fibrousmaterial adapted for use in manufacturing paper, paper board, andanalogous materials, fibrous threads adapted to be spun and woven, and

' other cellulose articles.

Another object consists in providing certain improvements in the methodwhereby advantageous results are obtained.

In the manufacture of sugar, the cane is crushed between rollers, in awell understood manner, and, as a result of this crushing operationthereis left the coarse fibrous element of the sugar cane, which is known asbagasse. This substance is produced in a very large quantity and, atpresent, it is commonly used as fuel for firing the power plants of thesugar factories which operate upon the cane. The material is not verysuitable as a fuel, largely because of its low calorific value but, thegreat amount produced calls for its use in such manner in the absence ofa more profitable employment of it. My invention contemplates utilizingthe bagasse in a much more profitable manner so that it will beeconomical to fire the factory furnaces with more efficient. fuel, suchas coal or oil,thereby bettering the manufacturing operations in thisrespect, in ad Previous efforts to utilize bagasse have consisted inattemptsto manufacture paper or heavy board, and have uniformlyembodied, in the-main, treating the bagasse to a more or less drasticdigestion with a caustic alkali or other chemicals, without previoustreat- Application filed March 25, 192s. Serial No. 97,452.

ment or preparation, and I have determined that, when the bagasse ofsugar cane is subjected to such a digestiontreatment, various substancesbound in with the bagasse, such as the complex carbo-hydrates and thelike, gelatinize, and the subsequent steps required to eliminate saidgelatinized substances greattion of the pith or parenchyma of the sugarcane. As a matter of fact, the defects in such previous paper oranalogous material have not been due to the pith, but have been due tothe presence in the pulp of varying amounts of sucrose, pentosans, andsimilar carbohydrates which, unless removed before the material isdigested in the ordinary course of manufacturing cellulose pulp by thesoda and other processes, decompose, change and combine with the alkalior acid used in such processes, thereby forming complex gelatinousmasses which are very difiicult to cook out of the pulp withoutexcessive use of chem-- icals, and resultant low yield because of thedestroying of a substantial percentage of the cellulose fibers by theviolence of the treatment. The portion of the said masses which are notentirely removed from the pulp, cause brittleness, poor bending, foldingand creasing qualities, and impart light, irregular spots in the paperor analogous products manufactured therefrom, and otherwise produceunsatisfactory results.

My present invention comprehends the treatment of the bagasse in such away that the said sucrose, pentosans, and similar car- -bo-hydrates, andthe like, are removed, or

transformed so as to nullify their injurious effects, before thedigesting of the fibrous portion or cellulose into paper pulp, thisbeing accomplished without injury to the fibrous material. Moreover, myinvention leaves the pithy cellulose portion of the fiber in a clean lstate attached to the fibers, so that the paper and the like,manufactured therefrom, will not embodvthe defects above named, and willgive better indications when tested for strength, as by Mullen tester,fold and other qualities; as well as producing a fiber which is of highquality and well adapted for textile uses and other purposes herembeforeIndicated.

Analysis of sugar cane reveals the fact that besides water and sucrose,it contains a number of complex carbo-hydrates of wholly or partiallyundetermined nature, and also a greater or lesser amount of celluloseand pen tosans. Such analysis further discloses that the fibrous portionof the cane retains, in mechanical or chemical combination with the ithor parenchyma, and together with the cellulose cells, a substantial partof the water content of the cane, as well as sucrose, dextrose,levulose, pentosans, (Xylan and araban), lignin complexes, and othersubstances. In either an alkaline or acid treatment, of any substantialintensity, some or all of these substances gelatinize and becomemeasurably or highly insoluble. Subsequent treatment arcomplishing theremoval of such gelatmized complexes, for instance by their destruction,is also accompanied by injury of a greater or lesser degree to thefibers of the cellulose part of the bagasse, the extent of which injurymay depend upon the strength of the digesting so lution, or the lengthof time of digestion treatment or the temperature thereof, or of any twoor all of these factors.

Having in mind these hitherto unsurmounted difficulties, my inventioncomprehends a treatment of the bagasse or fibrous elements of sugar canewhich separates, or transforms so as to nullify their injurious effects,the substances other than the fibrous elements from the latter withoutinjuring the Fibrous elements by said treatment and with outgelatinizing or otherwise acting upon the said substances so as torequire for their separation another treatment injuring the fibers.

Broadly speaking, this invention embodice the step of subjecting thebagasse or fibrous elements of sugar cane to a substantially neutral hotwater treatment at a temperature sufficient to dissolve or transform tosoluble orm. the said substances desired to be separated from thefibers. Such step is preferably conducted in the absence of air, and ata temperature of approximately 160 centigrade, with a pressure ofapproximately 6.35 kilograms per square centimeter. The water ispreferably pratically neutral such as, for instance, ordinary city watersupply. It may, however, be slightly acid or slightly alkaline withoutpreventing the substantial advantages of the invention from beingobtained. An important distinction between this ste of my invention andthe previously practiced art in this respect, re-

sides in the fact that I utilize what may be called hot water hydrolysisfor the separation of the above named, and analogous substances, fromthe fiber, instead of employing either an acid or alkaline hydrolysis.In colloquial language, it is the hot water which does the work in myinvention, instead of the acid or the alkali.

I realize that, upon treating the bagasse with the hot water, a certainamount of acidity is liberated by certain of the compounds containedtherein so that the condition of the treatment will be slightly acideven though the water supplied is neutral. This, however, does notdefeat the characteristic feature of my invention which involves theaddition to the mass of substantially neutral water as distinguishedfrom a chemical treatment with substantial amounts of extraneous acid oralkali, and it is this characteristic step that I refer to when Imention treating the fibrous part of the cane with substantially neutralwater.

In using the temperature referred to as approximately 160 centigrade, Ifind it desirable to go neither below nor much over that temperature.The action is not at all effective at a substantially lower temperatureand, at a temperature greater than about 173 centigrade, there isliability of serious injury to the fiber.

Such hot water treatment will remove the substances desired to beseparated, chiefly by directly or indirectly dissolving same withoutcausing gelatinization or the like, and it will not injure the nativeproperties of the fiber which are desirable for the purposeshereinbefore set forth.

The carrying out of this step in the absence of air is also a matter ofimportance because air, at high temperature or pressure, has a tendencyto attack and injure the fibers.

In practicing the method which embodies my invention. the bagasse as itcomes from the rolls of the sugar mill, usually containing about fiftypercent of moisture, is preferably deposited in open tanks or vats whichhave suitable agitating or stirring devices, such as paddles located inthe upper part. In the said tanks or vats the bagasse is washed by beingagitated in warm, but not boiling, water, until a portion of thesucrose, and other easily soluble substances are dissolved, and dirt andother foreign matter loosened and precipitated in the bottom of thetanks or vats. The bagasse will float at the top. This treatment mayvary in intensity according to the particular nature of the bagasse, buta treatment in water at about 90 centigrade for about one-half hour isordinarily adequate. Any person skilled in this art can readilydeterminethe temperature and time best suited to the particular qualityof bagasse that is presented to him.

Following the above washing, which is a preferred but-not necessarystep, the ba asse is removed from the tanks or vats and p aced in aclosed vessel, which I call an eliminator. Such vessel is quite similarto. a paper pulp digester, which is a well known apparatus,

and it is provided with a large opening for receiving the bagasse,relief cocks or other suitable devices for removin the air, the usualcontrolling and recor ing appurtenances, and discharge gates or outlet.After the eliminator has been filled to its substantial capacity,sufficient water is added to cover the bagasse, and the whole is raisedto a temperature of approximately 160 centi- 'rade and a pressure ofapproximately 6.35 kilograms per square centimeter. During thisproceeding provision is made for releasing any air and gases that mightbe present in the eliminator, by means of suitable cocks, vents, reliefvalves or the like. The mass is maintained at substantially thistemperature and pressure for a eriod of from, say, ten minutes to threeor our hours. This period of time depends mainly on the quality, age andgeneral condition of the bagasse.- As

remarked in connection with the preceding step, an operator skilled inthis art can readily determine the best period of time for theparticular bagasse he is treating.

Following this step, the bagasse is removed and thoroughly washed inopen vats or tanks while being agitated. In this washa ing, water atordinary temperature may be ter of a few hours.

employed, and it may be continued for a mat- The exactdetails of thisstep may, of course, be varied, within the skilled knowledge of theoperator, according to the particular bagasse undergoing treatment, and,in certain cases, this step may be omitted. In case the product isintended to be used for textile and analogous purposes it may bedesirable, at this time, to strip the fibers of their parenchymateoustissue by some suitable means, such as fluted rollers or stripperssimilar to those in common use for similar operations.

Thereafter the remaining fibrous mate-,1 rial, which has, by'th-epreceding steps, been freed from the objectionable substances previouslymentioned, may be dried in centrifugal dryers of standard type, or otherwell known or approved form of drying appara tus; compressed inhydraulic presses or the like, and shipped to the points of manufacture.Another suitable course is to press the fibrous material in hay presses,without previous drying. In hydraulic presses the material mustordinarily be dry or else it will be molded by the pressure, while thehay presses do not exclude the air or pack the material hard enough tocause molding, even though the material be wet at the time of pressure.If the paper or the like is to be manufactured at a nearby place, thefibrous material, without any drying, may be at once assed into the wellknown paper ulp -diggster. Whether or not the material be dried fore itis passed into the digester, the treatment therein may be conducted inthe usual manner, except that the treatment will recpiire much less inthe way of chemicals and t e course, the bagasse would be the startingmaterial because that is a common by-product obtainable in large volume,but I do not wish to have the application of this invention limited tobagasse as the initial material since, as above indicated, the caneitself may be employed.

Furthermore, it is a feature of this invention that I may utilize sugarcane which has been damaged with respect to its adaptability for themanufacture of sugar as, for instance, by. fires in the cane fields.Such damaged sugar cane is still suitable for treatment by my method andthe uninjured fibers can be separated and employed as indicated.

It should be mentioned that, in the manufacture of sugar, a materialpercentage of the sucrose available in the cane commonly remains in thebagasse. This may even equal three percent of the total sucrose. Whenthe bagasse is used as fuel, this sucrose is, of course, lost. Theherein described invention enables the saving of a considerable part ofthis previously lost sucrose because the waters which I employ inwashing and otherwise-treating thebagasse can be employed in the processof macerating the cane in the manufacture of the sugar. Thereby thesewaters will carry into the macerated cane the sucrose combined withthem, and the said sucrose will be recovered in the process of sugarmanufacture in the usual way. The said waters, furthermore, assist inthe maceration of the cane.

The immediate purpose and result of this invention is the production ofa cellulose ma at ordinary temperature, an

terial adapted for use generally in the manufacture of articles that maybe produced from such cellulose material and, therefore,

when I have referred to the manufacture of paper and the like and to usein the textile art, I have merely been illustrating two particularfields of employment of my inven-v tion, and do not desire saidreferences to limit the application of the invention, since it isadapted to a broad range of industrial employment as above indicated.

It will be understood that various changes may be resorted to in thesteps of the process, in the materials, and in the apparatus withoutdeparting from the spirit and scope of my invention, and hence I do notintend to be limited to the details herein set forth except as they maybe included in the claims.

What I claim is:

1. A method for recovering the fibrous material from sugar cane, whichincludes the step of treating the fibrous part of the cane withsubstantially neutral water at a temperature sufficient to remove ortransform most of the substances combined with the fibrous part, saidtreatment being carried out in the substantial absence of air.

2. A method for recovering the fibrous material from sugar cane, whichincludes the step of treating the fibrous part of the cane withsubstantially neutral Water at a temperature suflicient to remove -ortransform most of the substances combined with the fibrous part, saidtreatment being carried out at a pressure above atmospheric pressure andin the substantial absence of air.

3. A method for recovering the fibrous material from sugar cane, whichincludes the step of treating the fibrous part of the cane withsubstantially neutral water at a temperature of substantiallycentigrade, said treatment being carried out in the substantial absenceof air.

4. A method for recovering the fibrous material from sugar cane, whichincludes the step of treating the fibrous part of the cane withsubstantially neutral water at a temperature of substantially 160centigrade and an absolute pressure of aproximately 6.35 kilograms persquare centimeter, said treatment being carried out in the substantialabsence of air.

In testimony, that I claim the foregoing as my invention, I have signedmy name this 23rd day of March, 1926.

JOAQUIN JULIO de la ROZA, Senior.

